Let-off motion for looms



April 28, 1931. o.'v. PAYNE 1,803,142

' LET-OFF MOTION FOR LOOMS Filed March 14, 1929 3 Sheets-Sheet 1 I N V l/rl a/zzar I 0560/ fay/m April 28, 193-1. 7 b. v. PAYNE 1,803,142

LET-OFF MOTION FOR LOOMS Filed March 14, 1929 w 3 Sheets-Sheet 2 A ril 28, .1931. o. v. PAYNE 1,803,142

LET-OFF MOTION FOR LOOMS Filed March- 14, 1929 3 Sheets-Sheet 5 Fatented Apr. 28, I931 UNITED] STATES PATE NT OFFICE oscAR v PAYNE, OF woEoESTER, MASSACHUSETTS, ASsIGNoR To 'CBOMPTON & KNOWLES LOOM WORKS, oEwoEcEsTER, MASSACHUSETTS, A coEroRA IoN or MASSACHUSETTS LET-OFF MoTioN E03 'LooMs .1, Application filed Marchll, 1929. Serial No. 347,076.

This invention relates to means for regulating the tension on thewarp beam of'a loom. Uniformity of operation of such-devices has become increasingly important as the weavterialhas increased.

tension will be maintained substantially without variations, ual adjustment sate for changes in warp beam diameter. 9 In the preferred form, my improved let-off comprises a weight so connected to a warp beam that a substantially continuous winding up or lifting of the weight is accompanied by a substantially continuous downward readjustment thereof.

- My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appendedclaims. A preferred form-of the invention isshown in the drawings in which r Fig. 1 is a sideelevation of parts of a loom embodying. my improvements; a i Fig. 2 is a plan view of my improved letoff mechanism, looking in the direction of the arrow'2 in Fig. 1; i

Fig. 3 is an enlarged sectional end elevation of the let-offmechanism, taken along the line 33inFig.2;

Fig. 4 is a view similar to Fig. 3 but showing theparts in a different position;

Fig. 5 is a detail bottom view of parts of the let-off mechanism, looking in-the direction of the arrow 5 in Fig; 3;

Fig. 6 is a front elevation of parts of'the mechanism, the view being taken along the line 66 in Fig.3;

Fig; 7 is a detail sectional view, taken along the line 77 in Fig. 4;

Fig. 8 is a side elevation, of. a bell crank member to be Fig. 9 is a side elevation, modification.

,Referring to the drawings, .1 have shown portionsof a loom including a loom frame 10,

except as it may require manfrom time to time to compens partly in section, described; and showing a slight "IIIg Of very fine fabrics of silk or similar maandia lay 11 mounted on the'us'ual swords12 and swinging about a rock shaft'or pivot 14.

The lay 15, connected to the usualcrankshaft l6.

Warp threads W are drawn from a'warp beam B'having gudgeons or'journals 17 ro- It is the object of my invention'to provide I alet-off mechanism so designed that the warp.

tatably supported in open bearings 18. The warp threads breast beam 20 in the usual manner. i

A drum 22 (Figs. 5 and'6) is fixed on the journal or gudgeon 17 at one or both ends of the warp beam B and ispreferablyprovided with flanges '24at both endsflor edges of the drum. The Warp tension is produced by weights G suspended from a rope 30. 1A plurality of weights Gare commonly used,

and the number of weights may be varied to give the desired warp tension; r

The rope 30 is preferably spliced or otherwise upon oneloop of the rope 30. The two strands of the rope pass substantially around the drum 22, as indicated in- Figs. 5 and 6, and the end of the loop passes through aclip or lug 32, fixed on a friction band 34.

The band 34 substantially encircles the drum 22 between the two strands of rope 30 and is preferably formed as a strip of, sheet metal having aleather or other friction lining 36 (Fig. 3).

A block 38 issecured to one end of the friction band 32 and is provided with an opening 39 through which a hook bolt 40 is inserted. I

Theother end of the band 32 is pivotally connected to astud 42 extending through plates 44 mounted at each side of the band 32, the plates being held from displacement bypins'45 in the endsof the stud 42.

A bell crank 50 (Fig. 8) is forked-at its short end andis provided with openings 52 and .54 and-with a pocket 56. Thebell crank is pivotally mounted on a stud 58 extending through the-opening; 52 and supported in the side plates 44. A stud 60 is riveted in the openings 54which are formed in spaced cars at the forked end of the bell crank 40, as clearly shown in Fig. One end of a coil spring v62 is seated in W pass through a reed'19 on the lay 11 and are thendrawn forward over :the

made continuous and the weights G hang is oscillated by links or crank arms oted at 7 2 on the loom frame 10 and is positioned to engage the cam-like outer face of the bell crank 50. The arm 71 is connected by a link 74 (Fig. 1) to a stud 75 on the sword 12. Consequently, as the lay swings backward, the roll 70 will be moved toward the bell crank 50. 7

Having described the construction of my improved let-off, I will now describe the operation thereof.

It is recognized by those skilled in weaving that the most satisfactory let-off yet discovered is a simple weight hung directly on the periphery of a drum, such as the drum 22, connected to the gudgeon or supporting shaft of a warp'beam, the weight being raised as the beam is rotated to unwind the warp. Such a let-off is unvarying in its operation and provides an almost perfectly uniform tension on the warp, but this elementary construction cannot be used in practice, as the weight quickly reaches its upper limit of travel and then becomes inoperative.

With my improved construction, I have retained the advantages of the simple letoff above described, whileat'the same time avoiding its described limitation. This result I accomplish by providing a downward readjustment of the weight which is substantially continuous with the raising of the weight by the drawing ofi of the warp from the beam. 7 1

The friction of the rope 30 on the drum-22 is not in itself quite suflicient to raise the weight G as the drum 22 rotates when under weaving tension. When the friction of the band 32 is added to the friction of the rope 30, the combined friction is sufficient to grip the drum and to raise the Weight G as the drum is rotated.

If, however, the bell crank 50 is pushed toward the drum 22 by the roll 70, as indicated in Fig. 4, the effective length of the band 32 is increased by thev outward movement of thestud- 60 of the bell crank 50, and the weight G then causes the rope 30 and band 32 to slip on the drum 22 until the bell crank 50 has been moved upward out 1 of contact with the roll 70. The spring 62 then forces the bell-crank outward, tightening the band 32 and again causing the weight G to be supported on theperiphery of the drum 22 "In actual operation. the band 32 is thus re leased at substantially every beatof the lay and the downward adjustment of the weight G is very slight at each such release, but the combined adjusting movements are suflicient to oifset the rotation of the warp beam. The weight is thus in effect continually applied to the warp beam, while at the same time it is prevented from winding up to a point where it would become ineffective.

It will be noted also that when the weight is momentarily released, the lay is approaching back center, and that it is bound to the drum 22 as the lay swings forward for the beat-up.

- Actual tests of my improved let-off under operating conditions have shown that a surprisingly uniform tension is continuously maintained on the warp threads W, the device'being substantially equal in this respect to a simple weight hung directly on the drum, while at the same time it has the advantage of being continually self-adjusting.

While I have shown the bell crank 50 as beingengaged by a roll 70 on a movable arm 71 it will be obvious; that substantially similar results would be attained if the roll 7 0 and arm 71 were locked in fixed position, and this additional mode of operation is within the scope of my invention.

Such a construction is. shown in Fig. 9, where the roll is mounted on an arm 81 fixed to the loom frame, and is engaged by the bell crank 50 as it moves downward and clockwise. V

7 Having. thus described my. invention and the advantages thereof, I do-not wish to be limited to the details'herein disclosed; other- I claim is wise than as set forth in the claims, but what 1. In a loom let-off, a warp beam, a drum,

a weight, a rope frictionally wrapped substantially around said drum and supporting said weight, a combined band and connecting device entirely. encircling said drum, said bandfrictionally engaging said drum and to which a portion of said rope is attached, and releasing means controlled by the rotation of said beam by which the effective combined circumferential length of said band and connecting device is intermittently increased, said band being thereby released from said drum while said rope retainscontact therewith.

2. A combination in a forth in claim 1, in which a bell crank lever is connected between the ends of said band and a spring for moving said said band to grip said drum, and in which means is provided for moving said lever to intermittently release the frictional engagement of said band with said drum, said'lever being moved out of engagement with said moving means by the resultant rearward movement of said friction band.

3. The combination in a loom as set forth in claim 1, in which said releasing means inloom let-off as set lever to cause cludes a member actuated in fixed relation to the movement of the lay, and effective to release said band as the lay approaches back center.

4. A loom let-off comprising a warp beam, a drum, a friction band encircling and clamped around said drum in frictional engagement therewith, a weight, a rope connecting said weight to said band, said rope substantially encircling and frictionally engaging said drum, and means to intermittently decrease the friction of said band on said drum, said friction being restored as a direct result of rearward movement of said band relative to said drum.

5. In a loom let-01f, a warp beam, a drum, a weight, a rope on which said weight is supported said rope substantially encircling and frictionally engaging said drum, a device connecting said rope to said drum effective to produce a substantially continuous moving of the weight by said drum, a member movable in a fixed path and engaging said device to release the friction of said device on said drum when said device has been rotated with said drum in one direction into the path of said movable member and said device being moved in the opposite direction out of the path of said member I by said weight when said device is frictionally released from said drum.

In testimony whereof I have hereunto affixed my signature. I

OSCAR V. PAYNE. 

